1. Field of the Invention
The invention relates generally to medical devices. More specifically, the invention relates to intravascular embolic protection devices.
2. Related Technology
Embolic protection devices are percutaneously placed in a body vessel to prevent emboli from traveling and creating an undesirable embolism, e.g., pulmonary embolism. For example, vena cava filters are used for trapping emboli in the vena cava filter to prevent pulmonary embolism. Also, anti-platelet agents and anticoagulants may be used to breakdown blood clots. Moreover, snares and baskets (e.g., stone retrieval baskets) are used for retrieving urinary calculi. Additionally, occlusion coils are commonly used to occlude aneurysms and accumulate thrombi in a body vessel.
Treatments for a stenotic lesion provide a potential in releasing blood clots and other thrombi plaque in the vasculature of the patient. One example is the treatment for a carotid artery stenosis. Generally, carotid artery stenosis is the narrowing of the carotid arteries, the main arteries in the neck that supply blood to the brain. Carotid artery stenosis (also called carotid artery disease) is a relatively high risk factor for ischemic stroke. The narrowing is usually caused by plaque build-up in the carotid artery.
Carotid angioplasty is a more recently developed treatment for carotid artery stenosis. This treatment uses balloons and/or stents to open a narrowed artery. Carotid angioplasty is a procedure that can be performed via a standard percutaneous transfemoral approach with the patient anesthetized using light intravenous sedation. At the stenosis area, an angioplasty balloon is delivered to predilate the stenosis in preparation for stent placement. The balloon is then removed and exchanged via catheter for a stent delivery device. Once in position, a stent is deployed across the stenotic area. If needed, an additional balloon can be placed inside the deployed stent for post-dilation to make sure the struts of the stent are pressed firmly against the inner surface of the vessel wall. During the stenosis procedure however, there is a risk of such blood clots and thrombi being undesirably released into the blood flow within the vasculature.
Therefore, embolic protection devices, such as occlusive devices and filters, have been developed to trap and to prevent the downstream travel of the blood clots and thrombi. The filters are typically advanced downstream of a site that is to be treated and then expanded into an opened state to increase the filter area. The blood clots and thrombi can be captured in the opened filter while blood is still able to flow therethrough.
However, filter devices may fail to completely open within the blood vessel, leaving gaps between the filter outer surface and the blood vessel inner surface. These gaps may permit the above-described blood clots and thrombi to flow past the filter, unoccluded. As a result, the unoccluded blood clots and thrombi may thereby compromise the blood flow at a location distal from the treatment site.
Thus, there is a need to improve the positioning the expanding of the filter device within the blood vessel to effectively capture the unoccluded blood clots and thrombi.